Ultrasound of frequency 5.000 MHz reflected from red blood cells moving in an artery…
PHYSICS · Multi-part · AP · Physics 2: Algebra-based · Waves Sound and Physical Optics · Waves Sound and Physical Optics
Problem
Ultrasound of frequency 5.000 MHz reflected from red blood cells moving in an artery is found to show a frequency shift of 2.4 kHz. The speed of ultrasound in blood is v=1500 m s−1 .
(1) Explain why the appropriate formula for the frequency shift is fΔf=v2u , where u is the speed of the blood cells.
(2) Estimate the speed of the blood cells.
(3) In practice, a range of frequency shifts is observed. Explain this observation.